Unsaturated polyester resin compositions

ABSTRACT

The present invention relates to a pre-accelerated resin composition, characterized in that the resin composition comprises an unsaturated polyester resin and/or a vinyl ester resin, a soluble copper compound and a heterocyclic aromatic amine and which resin composition is essentially free of cobalt. The present invention further relates to a two component composition in which the first component comprises such a resin composition and in which the second component comprises an organic peroxide.

This application is a divisional of commonly owned copending U.S.application Ser. No. 12/739,898, filed Sep. 1, 2010, which is thenational phase application under 35 USC §371 of PCT/EP2008/064265, filedOct. 22, 2008, which designated the US and claims benefit of EP PatentApplication No. 07020905.1, filed Oct. 25, 2007, the entire contents ofeach of which are hereby incorporated by reference.

The invention relates to a pre-accelerated resin composition comprisingan unsaturated polyester resin and/or a vinyl ester resin. The presentinvention also relates to two-component compositions containing a firstcomponent A and a second component B; the first component containing anunsaturated polyester resin and/or a vinyl ester resin and the secondcomponent containing a peroxide. In particular, the present inventionrelates to two-component unsaturated polyester resin or vinyl esterresin compositions for structural parts.

The present invention further also relates to objects and structuralparts prepared from such two-component compositions. The presentinvention finally also relates to a process for curing suchtwo-component compositions.

As used herein, the term “two-component system” refers to systems wheretwo separate components (A and B) are being spatially separated fromeach other, for instance in separate cartridges or the like, and isintended to include any system wherein each of such two separatecomponents (A and B) may contain further separate components. Thecomponents are combined at the time the system is used.

As meant herein, objects and structural parts are considered to have athickness of at least 0.5 mm and appropriate mechanical properties. Theterm “objects and structural parts” as meant herein also includes curedresin compositions as are used in the field of chemical anchoring,construction, roofing, flooring, windmill blades, containers, tanks,pipes, automotive parts, boats, etc.

All polyester resins, by their nature, undergo some changes over timefrom their production till their actual curing. One of thecharacteristics where such changes become visible is the gel-time drift.The state of the art unsaturated polyester resin systems generally arebeing cured by means of initiation systems. In general, such unsaturatedpolyester resin systems are cured under the influence of peroxides andare accelerated (often even pre-accelerated) by the presence of metalcompounds, especially cobalt salts, as accelerators. Cobalt naphthenateand cobalt octanoate are the most widely used accelerators. In additionto accelerators, the polyester resins usually also contain inhibitorsfor ensuring that the resin systems do not gellify prematurely (i.e.that they have a good storage stability). Furthermore, inhibitors,especially phenolic inhibitors, are being used to ensure that the resinsystems have an appropriate gel time and/or for adjusting the gel-timevalue of the resin system to an even more suitable value.

Most commonly, in the state of the art, polymerization initiation ofunsaturated polyester resins, etc. by redox reactions involvingperoxides, is accelerated or pre-accelerated by a cobalt compound incombination with another accelerator.

It has now surprisingly been found that a soluble copper compound incombination with a heterocyclic aromatic amine acts as an acceleratorfor the peroxide curing of an unsaturated polyester resin and/or vinylester resin. The resin composition contains less than 0.01 mmol cobaltper kg primary resin system. Preferably, the resin composition containsless than 0.001 mmol Co per kg primary resin system. Most preferably theresin composition is free of cobalt.

According to the present invention, compositions having good curingproperties can be obtained, i.e. the compositions according to theinvention have short gel time, short peak time and/or high peaktemperature. In the curing of unsaturated polyester resins or vinylesters, gel time is a very important characteristic of the curingproperties. In addition also the time from reaching the gel time toreaching peak temperature, and the level of the peak temperature (higherpeak temperature generally results in better curing) are important. Inaddition, the compositions according to the present invention can beobtained with reduced gel-time drift tendency.

U.S. Pat. No. 4,524,177 discloses that copper compounds in an amountsfrom 0.0005 to 0.2% by weight, preferably from 0.001 to 0.05% by weight,based on the ethylenically unsaturated compound to be polymerized, canbe used for basic stabilization of the ethylenically unsaturatedcompounds to be polymerized. Thus, this document teaches that copper isan inhibitor. Similar, GB834286 teaches that small amounts of a solubleform of copper in the range 0.25 ppm to 10 ppm of copper improves theinhibiting properties of inter alias aromatic amines, quaternaryammonium salts and amine salts. U.S. Pat. No. 6,329,475 furthermoreteaches that an amine acts as an inhibitor for catalyst compositioncontaining copper. WO-A-9012824 discloses an accelerator composition forthe curing of unsaturated polyester resins comprising a complex ofcertain metal salts with organic nitrogen compounds. Preferably, themetal is selected from copper, vanadium, lithium, nickel, iron,magnesium and cobalt. For copper, an amount of from 0.1 to 10 ppm ismentioned. Furthermore, according to this document, higher amounts ofcopper do not further contribute to the activity. However, none of thedocuments cited above disclose that copper in combination with aheterocyclic aromatic amine can be used as accelerator for the radicalcuring of unsaturated polyesters or vinyl esters.

An additional advantage of the present invention is that compositionswith relatively low gel-time drift tendency can be obtained.

As meant herein the term gel-time drift (for a specifically selectedperiod of time, for instance 30 or 60 days) reflects the phenomenon,that—when curing is performed at another point of time than at thereference standard moment for curing, for instance 24 hours afterpreparation of the resin—the gel time observed is different from that atthe point of reference. For unsaturated polyester resins, as cangenerally be cured under the influence of peroxides, gel time representsthe time lapsed in the curing phase of the resin to increase intemperature from 25° C. to 35° C. Normally this corresponds to the timethe fluidity (or viscosity) of the resin is still in a range where theresin can be handled easily. In closed mould operations, for instance,this time period is very important to be known. The lower the gel-timedrift is, the better predictable the behaviour of the resin (and theresulting properties of the cured material) will be.

W. D. Cook et al. in Polym. Int. Vol. 50, 2001, at pages 129-134describe in an interesting article various aspects of control of geltime and exotherm behaviour during cure of unsaturated polyester resins.They also demonstrate how the exotherm behaviour during cure of suchresins can be followed. FIGS. 2 and 3 of this article show the gel timesin the bottom parts of the exotherms measured. Because these authorsfocus on the exotherms as a whole, they also introduced some correctionof the exotherms for heat loss. As can be seen from the figures,however, such correction for heat loss is not relevant for gel timesbelow 100 minutes.

Gel time drift (hereinafter: “Gtd”) can be expressed in a formula asfollows:

Gtd=(T_(25→35° C. at y-days)−T_(25-35° C. after mixing))/T_(25→35°)_(C. after mixing)×100%   (formula 1)

In this formula T_(25→35° C.) (which also might be represented byT_(gel)) represents, as mentioned above, the time lapsed in the curingphase of the resin to increase in temperature from 25° C. to 35° C. Theadditional reference to “at y days” shows after how many days ofpreparing the resin the curing is effected.

Most commonly, in the state of the art, polymerization initiation ofunsaturated polyester resins, etc. by redox reactions involvingperoxides, is accelerated or pre-accelerated by a cobalt compound incombination with another accelerator.

An excellent review article of M. Malik et al. in J. M. S.—Rev Macromol.Chem. Phys., C40(2&3), p. 139-165 (2000) gives a good overview of thecurrent status of resin systems. Curing is addressed in chapter 9. Fordiscussion of control of gel time reference can be made to the articleof Cook et al. as has been mentioned above. Said article, however, doesnot present any hint as to the problems of gel-time drift as are beingsolved according to the present invention.

The phenomenon of gel-time drift, indeed, so far got quite littleattention in the literature. Most attention so far has been given inliterature to aspects of acceleration of gel time in general, and toimproving of pot-life or shelf life of resins. The latter aspects,however, are not necessarily correlated to aspects of gel-time drift,and so, the literature until now gives very little suggestions as topossible solutions for improvement of (i.e. lowering of) gel-time drift.

Accordingly, for the unsaturated polyester resins and vinyl ester resinsas are part of the current state of the art there is still need forfinding resin systems showing reduced gel-time drift tendency, or inother words, resin systems having only slight gel-time drift when curedwith a peroxide. Preferably the mechanical properties of the resincomposition after curing with a peroxide are unaffected (or improved) asa result of the changes in the resin composition for achieving thereduced gel-time drift. Moreover, for environmental reasons, thepresence of cobalt in the resins is less preferred.

The unsaturated polyester resin or vinyl ester resin as is comprised inthe compositions according to the present invention, may suitably beselected from the unsaturated polyester resins or vinyl ester resin asare known to the skilled man. Examples of suitable unsaturated polyesteror vinyl ester resins to be used as basic resin systems in the resins ofthe present invention are, subdivided in the categories as classified byMalik et al., cited above.

-   -   (1) Ortho-resins: these are based on phthalic anhydride, maleic        anhydride, or fumaric acid and glycols, such as 1,2-propylene        glycol, ethylene glycol, diethylene glycol, triethylene glycol,        1,3-propylene glycol, dipropylene glycol, tripropylene glycol,        neopentyl glycol or hydrogenated bisphenol-A. Commonly the ones        derived from 1,2-propylene glycol are used in combination with a        reactive diluent such as styrene.    -   (2) Iso-resins: these are prepared from isophthalic acid, maleic        anhydride or fumaric acid, and glycols. These resins may contain        higher proportions of reactive diluent than the ortho resins.    -   (3) Bisphenol-A-fumarates: these are based on ethoxylated        bisphenol-A and fumaric acid.    -   (4) Chlorendics: are resins prepared from chlorine/bromine        containing anhydrides or phenols in the preparation of the UP        resins.    -   (5) Vinyl ester resins: these are resins, which are mostly used        because of their hydrolytic resistance and excellent mechanical        properties, as well as for their low styrene emission, are        having unsaturated sites only in the terminal position,        introduced by reaction of epoxy resins (e.g. diglycidyl ether of        bisphenol-A, epoxies of the phenol-novolac type, or epoxies        based on tetrabromobisphenol-A) with (meth)acrylic acid. Instead        of (meth)acrylic acid also (meth)acrylamide may be used.

Besides these classes of resins also so-called dicyclopentadiene (DCPD)resins can be distinguished as unsaturated polyesters. As used herein, avinyl ester resin is a (meth)acrylate functional resin. Besides thevinyl ester resins as described in Malik et al., also the class of vinylester urethane resins (also referred to urethane methacylate resins) canbe distinguished as vinyl ester resins. Preferably, the vinyl ester usedin the present invention is a resin obtained by the esterification of anepoxy resin with (meth)acrylic acid or (meth)acrylamide.

All of these resins, as can suitably used in the context of the presentinvention, may be modified according to methods known to the skilledman, e.g. for achieving lower acid number, hydroxyl number or anhydridenumber, or for becoming more flexible due to insertion of flexible unitsin the backbone, etc. The class of DCPD-resins is obtained either bymodification of any of the above resin types by Diels-Alder reactionwith cyclopentadiene, or they are obtained alternatively by firstreacting maleic acid with dicyclopentadiene, followed by the resinmanufacture as shown above.

Of course, also other reactive groups curable by reaction with peroxidesmay be present in the resins, for instance reactive groups derived fromitaconic acid, citraconic acid and allylic groups, etc. Accordingly, theunsaturated polyester resins or vinyl ester resins used in the presentinvention may contain solvents. The solvents may be inert to the resinsystem or may be reactive therewith during the curing step. Reactivesolvents are particularly preferred. Examples of suitable reactivesolvents are styrene, α-methylstyrene, (meth)acrylates,N-vinylpyrrolidone and N-vinylcaprolactam.

The unsaturated polyester resins and vinyl ester resins as are beingused in the context of the present invention may be any type of suchresins, but preferably are chosen from the group of DCPD-resins,iso-phthalic resins and ortho-phthalic resins and vinyl ester resins.More detailed examples of resins belonging to such groups of resins havebeen shown in the foregoing part of the specification. More preferably,the resin is an unsaturated polyester resin preferably chosen from thegroup of DCPD-resins, iso-phthalic resins and ortho-phthalic resins.

The resin composition of the two-component composition according to thepresent invention generally contains less than 5 wt. % water.

The inventors have surprisingly found that an efficient curing with lowamounts of heterocyclic aromatic amine, preferably according to formula(1) can be obtained

In which A=N, CR; B═N, CR; and at least one of A and B is N; R, R₁,R₂═C₁-C₂₀ alkyl, C₆-C₂₀ aryl , C₇-C₂₀ alkylaryl, C₇-C₂₀ arylalkyl inwhich the aryl groups can be further substituted and in which a ringstructure can be formed between R₁ and R₂, R₁ and R, R₂ and R and/or R₁,R₂ and R. As examples of resulting ring structures, benzene, cyclicalkenes can be envisaged.

The amount of heterocyclic aromatic amine preferably lies between 0.001and 1000 mmol/ kg primary resin system, more preferably between 0.1 and100 most preferably between 1 and 50 mmol/ kg primary resin system.

The most preferred heterocyclic aromatic amines are imidazole, pyrazoleand 1,2,3-triazolopyridine or derivatives thereof. Imidazole and itsderivatives are especially preferred, being a very active co-acceleratorat low amount by weight.

The soluble copper compound may be any copper compound which is solublein the primary resin system at room temperature. In the light ofsolubility of the copper compound in the primary resin system, thecopper compound is preferably a copper salt, more preferably the coppersalt is a copper carboxylate. It will be clear that, instead of a singlecopper compound also a mixture of copper compounds can be used.Preferably, the soluble copper compound is an organic copper compound.

The resin composition according to the present invention comprisessoluble copper compound and heterocyclic aromatic amines in such anamount that an effective curing takes place.

Preferably, the amount of the soluble copper compound lies between 0.001and 2000 mmol/kg primary resin system, more preferably between 0.1 and200 and even more preferably between 1 and 100 mmol/ kg primary resinsystem.

The copper is more preferably present in the resin composition in anamount of at least 20 ppm (relative to the primary resin system) (0.3mmol Cu per kg of primary resin system), preferably in an amount of atleast 60 ppm Cu. The upper limit of the copper content is not verycritical, although for reasons of cost efficiency of course no extremelyhigh concentrations will be applied. Generally the concentration of thecopper compound in the primary resin system will be such that the copperis present in an amount lower than 2000 ppm Cu (relative to the primaryresin system) (31 mmol Cu per kg of primary resin system), preferablylower than 1000 ppm Cu.

For understanding of the invention, and for proper assessment of theamounts of copper compound and heterocyclic aromatic amine to be presentin the resin composition, the term “primary resin system” as used hereinis understood to mean the total weight of the resin, but excluding anyfillers as may be used when applying the resin system for its intendeduses. The primary resin system therefore consists of the unsaturatedpolyester resin or vinyl ester resin, any additives present therein(except for the peroxide component that is to be added shortly beforethe curing) soluble in the resin, such as accelerators, promoters,inhibitors, low-profile agents, colorants (dyes), thixotropic agents,release agents etc., as well as styrene and/or other solvents as mayusually be present therein. The amount of additives soluble in the resinusually may be as from 1 to 25 wt. % of the primary resin system; theamount of styrene and/or other solvent may be as large as up to 50 wt. %of the primary resin system. The primary resin system, however,explicitly does not include compounds not being soluble therein, such asfillers (e.g. glass or carbon fibers), talc, clay, solid pigments (suchas, for instance, titanium dioxide (titanium white)), flame retardants,e.g. aluminum oxide hydrates, etc.

The molar ratio between the soluble copper compound to heterocyclicaromatic amine is preferably between 0.5 and 50, more preferably between1 and 10.

The inventors have further found that the curing can be performed evenmore efficient when the resin composition further comprises a 1,3-dioxocompound. An advantage of the presence of a 1,3-dioxo compound is thatthe curing is faster.

The 1,3-dioxo compound is preferably a compound having the followingformula:

whereby

-   X, Y═H, C₁-C₂₀ alkyl, C₆-C₂₀ aryl, C₇-C₂₀ alkylaryl, C₇-C₂₀    arylalkyl, part of a polymer chain, OR₅, NR₅R₆;-   R₃, R₄, R₅, and R₆ each individually may represent hydrogen (H), or    a C₁-C₂₀ alkyl, C₆-C₂₀ aryl, C₇-C₂₀ alkylaryl or C₇-C₂₀ arylalkyl    group, that each optionally may contain one or more hetero-atoms    (e.g. oxygen, phosphor, nitrogen or sulphur atoms) and/or    substituents;-   a ring may be present between R₃ and R₄, R₃ and R₅, and/or between    R₄ and R₆;-   R₅ and/or R₆ may be part of a polymer chain, may be attached to a    polymer chain or may contain a polymerizable group. In one    embodiment, X and/or Y are/is C₁-C₂₀ alkyl and/or C₆-C₂₀ aryl.    Preferably, X and/or Y are/is a methyl group. Preferably, the    1,3-dioxo compound is acetylaceton. In another and more preferred    embodiment X and/or Y are/is NR₅R₆. The 1,3-dioxo compound may be a    polymer or is polymerizable. Preferably, the 1,3-dioxo compound is    acetoacetamide as the presence of acetoacetamides in the resin    composition of the present invention results in faster curing.

Preferably, the amount of the 1,3-dioxo compound is from 0.05 to 5% byweight, calculated on the total weight of the primary resin system ofthe resin composition. More preferably, amount of the 1,3-dioxo compoundis from 0.5 to 2% by weight.

The 1,3-dioxo compound is preferably selected from the group of1,3-diketones,1,3-dialdehydes, 1,3-ketoaldehydes, 1,3-ketoesters, and1,3-ketoamides.

In a further preferred embodiment of the present invention, the resincomposition also contains one or more radical inhibitors. Morepreferably, the resin compositions according to the invention containone or more radical inhibitors preferably chosen from the group ofphenolic compounds, stable radicals like galvinoxyl and N-oxyl basedcompounds, benzoquinones, catechols and/or phenothiazines.

The amount of radical inhibitor as used in the context of the presentinvention, may, however, vary within rather wide ranges, and may bechosen as a first indication of the gel time as is desired to beachieved. Preferably, the amount of phenolic inhibitor is from about0.001 to 35 mmol per kg of primary resin system, and more preferably itamounts to more than 0.01, most preferably more than 0.1 mmol per kg ofprimary resin system. The skilled man quite easily can assess, independence of the type of inhibitor selected, which amount thereof leadsto good results according to the invention.

Suitable examples of radical inhibitors that can be used in the resincompositions according to the invention are, for instance,2-methoxyphenol, 4-methoxyphenol, 2,6-di-t-butyl-4-methylphenol,2,6-di-t-butylphenol, 2,4,6-trimethyl-phenol,2,4,6-tris-dimethylaminomethyl phenol,4,4′-thio-bis(3-methyl-6-t-butylphenol), 4,4′-isopropylidene diphenol,2,4-di-t-butylphenol, 6,6′-di-t-butyl-2,2′-methylene di-p-cresol,hydroquinone, 2-methylhydroquinone, 2-t-butylhydroquinone,2,5-di-t-butylhydroquinone, 2,6-di-t-butylhydroquinone,2,6-dimethylhydroquinone, 2,3,5-trimethylhydroquinone, catechol,4-t-butylcatechol, 4,6-di-t-butylcatechol, benzoquinone,2,3,5,6-tetrachloro-1,4-benzoquinone, methylbenzoquinone,2,6-dimethylbenzoquinone, napthoquinone,1-oxyl-2,2,6,6-tetramethylpiperidine,1-oxyl-2,2,6,6-tetramethylpiperidine-4-ol (a compound also referred toas TEMPOL), 1-oxyl-2,2,6,6-tetramethylpiperidine-4-one (a compound alsoreferred to as TEMPON), 1-oxyl-2,2,6,6-tetramethyl-4-carboxyl-piperidine(a compound also referred to as 4-carboxy-TEMPO),1-oxyl-2,2,5,5-tetramethylpyrrolidine,1-oxyl-2,2,5,5-tetramethyl-3-carboxylpyrrolidine (also called3-carboxy-PROXYL), aluminium-N-nitrosophenyl hydroxylamine,diethylhydroxylamine, phenothiazine and/or derivatives or combinationsof any of these compounds. Preferably, the inhibitor is selected fromthe group of phenothiazines, phenols, hydroquinones, benzoquinones,catechols and N-oxyl compounds.

Advantageously, the amount of radical inhibitor in the resin compositionaccording to the invention is in the range of from 0.0001 to 10% byweight, calculated on the total weight of the primary resin system ofthe resin composition. More preferably, the amount of radical inhibitorin the resin composition is in the range of from 0.001 to 1% by weight.

The resin compositions according to the invention preferably furthercomprises one or more reactive diluents, preferably in an amount of atleast 5 weight % and generally at most 80 wt. %. Such reactive diluentsare especially relevant for reducing the viscosity of the resin in orderto improve the resin handling properties, particularly for being used intechniques like vacuum injection, etc. However, the amount of suchreactive diluent in the resin composition according to the invention isnot critical. Examples of suitable reactive diluents are styrene, vinyltoluene, α-methyl styrene, tert butyl styrene, methyl methacrylate(MMA), hydroxyethyl methacrylate (HEMA), hydroxypropyl methacrylate(HPMA), vinyl ethers, vinyl esters, butanediol dimethacrylate (BDDMA),triethylene glycol dimethacrylate (TEGDMA), trimethylolpropanetrimethacryate (TMPTMA), phenoxyethyl methacrylate (PEMA),N-vinylpyrrolidone and N-vinylcaprolactam. Preferably, the reactivediluent is a methacrylate and/or styrene.

The present invention further relates to a two-component compositioncomprising a first component A and a second component B, wherein thefirst component being a resin composition as described above and thesecond component comprises a peroxide compound.

The peroxides used for the B component can be any peroxide known to theskilled man. Such peroxides include organic and inorganic peroxides,whether solid or liquid; also hydrogen peroxide may be applied. Examplesof suitable peroxides are, for instance, peroxy carbonates (of theformula —OC(O)O—), peroxyesters (of the formula —C(O)OO—),diacylperoxides (of the formula —C(O)OOC(O)—), dialkylperoxides (of theformula —OO—), etc. The peroxides can also be oligomeric or polymeric innature. An extensive series of examples of suitable peroxides can befound, for instance, in US 2002/0091214-A1, paragraph [0018]. Theskilled man can easily obtain information about the peroxides and theprecautions to be taken in handling the peroxides in the instructions asgiven by the peroxide producers.

Preferably, the peroxide is chosen from the group of organic peroxides.Examples of suitable organic peroxides are: tertiary alkylhydroperoxides (such as, for instance, t-butyl hydroperoxide), otherhydroperoxides (such as, for instance, cumene hydroperoxide), thespecial class of hydroperoxides formed by the group of ketone peroxides(perketones, being an addition product of hydrogen peroxide and aketone, such as, for instance, methyl ethyl ketone peroxide andacetylacetone peroxide), peroxyesters or peracids (such as, forinstance, t-butyl peresters, benzoyl peroxide, peracetates andperbenzoates, lauryl peroxide, including (di)peroxyesters), perethers(such as, for instance, peroxy diethyl ether). Often the organicperoxides used as curing agent are tertiary peresters-or tertiaryhydroperoxides, i.e. peroxy compounds having tertiary carbon atomsdirectly united to an —OO-acyl or —OOH group. Clearly also mixtures ofthese peroxides with other peroxides may be used in the context of thepresent invention. The peroxides may also be mixed peroxides, i.e.peroxides containing any two of different peroxygen-bearing moieties inone molecule. Preferably, the peroxide used in the B component isselected from the group comprising hydroperoxides and peresters.

The present invention further relates to a process for radically curinga resin composition, characterized in that the curing is performedstarting from a two-component composition as described above.Preferably, the curing is effected at a temperature in the range of from−20 to +200° C., preferably in the range of from −20 to +100° C., andmost preferably in the range of from −10 to +40° C.

It has been found that the radical curing of a two-component compositionaccording to the invention can be effected essentially free of cobaltand even in the absence of cobalt. Essentially free of cobalt means thatthe cobalt concentration in the resin composition is less than 0.01 mmolcobalt per kg primary resin system.

The two component unsaturated polyester or vinyl ester resincompositions according to the present invention can be applied in allapplications as are usual for such types of resins. In particular theycan suitably used in closed mould applications, but they also can beapplied in open mould applications. For closed mould applications it isespecially important that the manufacturer of the closed mould productsreliably can use the favorable polymerization characteristics of the twocomponent resin system according to the invention. End segments wherethe two components unsaturated polyester resin or vinyl ester resinsystems according to the present invention can be applied are alsomarine applications, chemical anchoring, roofing, construction,relining, pipes & tanks, flooring, windmill blades, etc. That is to say,the two component resin systems according to the invention can be usedin all known uses of unsaturated polyester resins and vinyl esterresins.

Preferably the two component system according to the invention or thecomposition obtained by the process according to the invention is usedin marine applications like boats, chemical anchoring, roofing,construction, relining, pipes & tanks, flooring, windmill blades,containers, tanks, pipes, automotive parts.

Finally, the present invention relates to objects or structural partsobtained from a two component composition as described above.

The invention is now demonstrated by means of a series of examples andcomparative examples. All examples are supportive of the scope ofclaims. The invention, however, is not restricted to the specificembodiments as shown in the examples.

Experimental Part

The resins used for curing are commercially available products from DSMComposite Resins B. V., Schaffhausen, Switzerland, and and in additionthereto also a resin -hereinafter referred to as Resin A- wasspecifically prepared on behalf of the inventors for being used in thetests. The peroxides used for curing are commercially available productsfrom Akzo Nobel Inc.

Preparation of Resin A

184.8 g of propylene glycol (PG), 135.8 g of diethylene glycol (DEG),216.1 g of phthalic anhydride (PAN), 172.8 g of maleic anhydride (MAN),and 0.075 g 2-t-butylhydroquinone were charged in a vessel equipped witha reflux condenser, a temperature measurement device and inert gasinlet. The mixture was heated slowly by usual methods to 205° C. At 205°C. the mixture was kept under reduced pressure until the acid valuereached a value below 16 mg KOH/g resin and the falling ball viscosityat 100° C. was below 50 dPa·s. Then the vacuum was relieved with inertgas, and the mixture was cooled down to 130° C., and thereafter thesolid UP resin so obtained was transferred to a mixture of 355 g ofstyrene and 0.07 g of mono-t-butyl-hydroquinone and was dissolved at atemperature below 80° C. The final resin viscosity reached at 23° C. was640 mPa·s, and the Non Volatile Matter content was 64.5 wt. %.

Monitoring of Curing

In most of the Examples and Comparative Examples presented hereinafterit is mentioned, that curing was monitored by means of standard gel timeequipment. This is intended to mean that both the gel time (T_(gel) orT_(25→35° C.)) and peak time (T_(peak) or T_(25→peak)) were determinedby exotherm measurements according to the method of DIN 16945 whencuring the resin with the peroxides as indicated in the Examples andComparative Examples. The equipment used therefore was a Soform geltimer, with a Peakpro software package and National Instrumentshardware; the waterbath and thermostat used were respectively Haake W26,and Haake DL30.

For some of the Examples and Comparative Examples also the gel-timedrift (Gtd) was calculated. This was done on the basis of the gel timesdetermined at different dates of curing according to formula 1:

Gtd=(T_(25→35° C. at y-days)−T_(25→35° C. 0 after mixing)/T_(25→35° C. after mixing)×100%  (formula 1)

with “y” indicating the number of days after mixing.

EXAMPLES 1-2 AND COMPARATIVE EXAMPLES A-D

Formulations were prepared based on 90 g resin A combined with 10 gstyrene, 0.24 g Cu naphtenate in spirits (8% Cu) and various amounts ofamines. Curing was performed employing 3% Butanox M50.

The cure was monitored using the gel time equipment described above andthe results are shown in table 1.

TABLE 1 Amount Tgel T peak Temp ex amine (g) (min) (min) ° C. 1imidazole 0.035 10.9 18.4 181 0.067 12.8 20.5 180 2 pyridine 0.035 32.447.8 135 0.067 23.2 35.5 146 Comp A morpholine 0.035 211.4 240.6 1180.067 110.3 121.4 118 Comp B N,N-dimethyl 0.035 177 211.6 38ethanolamine 0.067 109.7 153.6 53 Comp C triethylamine 0.035 — 320.7 330.067 125.1 170.4 73 Comp D aniline 0.035 — 829.7 28 0.067 — 733.9 28

These examples demonstrate that efficient curing with low amounts ofamine only takes place when employing heterocyclic aromatic aminesaccording to the invention.

EXAMPLES 3-9

Formulations were prepared based on 90 g resin A combined with 10 gstyrene, 0.24 g Cu naphtenate in spirits (8% Cu) and various amounts ofheterocyclic aromatic amines. Curing was performed employing 3% ButanoxM50.

The cure was monitored using the gel time equipment described above andthe results are shown in table 2.

TABLE 2 Gel times with various amounts of various amines 5 mmol 50 mmol100 mmol amine/kg amine/kg amine/kg Ex amine resin resin resin 3Imidazole 9.6 37.6 41.6 4 Pyrazole 36.8 118 142.8 5 1,2,3-triazolo 10.416.8 20 pyridine 6 pyridine 31.5 28 34 7 pyridazine 74 10 7 8 oxazole140 83 90 9 1,2,4-triazolo 94 14 6.5 pyrimidine

These results indicate that with low amounts of aromatic heterocyclicamines i.e. in the range of 0.3% a sufficient curing can be obtained.Furthermore these results clearly show that using imidazole, pyrazoleand 1,2,3-triazolo pyridine, i.e. structures according to formula 1 evenat 5 mmol/kg resin e.g. amounts in the range of 0.03% an efficientcuring takes place.

EXAMPLES 10-11

Formulations were prepared based on 100 g of Daron XP 45-A-2, differentamounts of Cu naphtenate in spirits (8% Cu) and different amounts ofimidazole. Curing was performed employing 2% Butanox M50. The cure wasmonitored using the gel time equipment described above and the resultsare shown in table 3.

TABLE 3 Copper Amount 8% of copper Imidazole Tgel T peak ex (g) (ppm)(g) (min) (min) Temp ° C. 10 0.0375 30 0.0064 119.2 145.9 88 11 1.25011000 0.2143 26.6 38.2 135

These examples demonstrate that with a similar ratio ofcopper-imidazole, low and high amounts of copper can be used for curinga resin.

EXAMPLES 12-14

Formulations were prepared based on 90 g resin A combined with 10 gstyrene, 0.24 g Cu naphtenate in spirits (8% Cu) and 0.04 g imidazole.Curing was performed employing 3% of various peroxides. The cure wasmonitored using the gel time equipment described above and the resultsare shown in table 4.

TABLE 4 Ex peroxide Tgel (min) T peak (min) Temp ° C. 12 Butanox M50 1018 176 13 Trigonox 44B 48 59 164 14 Cyclonox LE50 8 12 123

These experiments clearly demonstrate that various peroxides can beemployed with the accelerator system according to the invention.

EXAMPLES 15-18

Formulations were prepared based on 100 g of various resin systems, 0.23g Cu naphtenate in spirits (8% Cu) and 0.04 g imidazole. Curing wasperformed employing 3% Butanox M50. The cure was monitored using the geltime equipment described above and the results are shown in table 5.

TABLE 5 ex resin Tgel (min) T peak (min) Temp ° C. 15 A/styrene 11.4 20170 (90/10) 16 Palatal P69- 49.7 67.6 147 02/styrene (90/10 17 PalatalP6- 141.1 160 144 01/styrene (90/10) 18 Daron-XP45- 62.5 73.7 156 A2

These examples clearly demonstrate that various resins can be used.

EXAMPLES 19-20

Formulations were prepared based on 90 g of various resin in 10 gstyrene, 0.23 g Cu naphtenate in spirits (8% Cu) , 0.04 g imidazole and0.01 g t-butylcatechol. Curing was performed employing 3% Butanox M50.The cure was monitored using the gel time equipment described above andthe results are shown in table 6.

TABLE 6 ex Resin Tgel (min) T peak (min) Temp ° C. 19 A 18.4 28.9 166 20Palatal P69-02 58.6 76.5 144

These results demonstrate that the cure characteristics can be tuned byemploying inhibitors.

EXAMPLE 21

A formulation was prepared based on 180 g resin A, 20 g styrene, 0.46 gCu naphtenate (8%) and 0.08 g imidazole. After stirring the mixture for5 minutes the mixture was dived in 2 portions of 100 g each. The firstportion was cured immediately with Butanox M50 yielding similar curecharacteristics as described in example 15 and the second portion wascured after 28 days of storage yielding Tgel=11.7, Tpeak=19.4 andpeaktemperature of 178° C. This corresponds to a gel time drift of only3% after 28 days.

EXAMPLE 22

A formulation was prepared based on 180 g Palatal P6-01, 20 g styrene,0.46 g Cu naphtenate (8%) and 0.08 g imidazole. After stirring themixture for 5 minutes the reactivity of the mixture was dived in 2portions of 100 g each. The first portion was cured immediately withButanox M50 yielding similar cure characteristics as described inexample 17 and the second portion was cured after 91 days of storageyielding Tgel32 139.5, Tpeak=159 and peaktemperature of 140° C. Thiscorresponds to a gel time drift of only −1% after 91 days of storage.

Examples 21 and 22 clearly demonstrate that employing the cure systemsaccording to the invention drift free pre accelerated resins can beobtained.

EXAMPLE 23

A formulation was prepared based on 100 g Palatal P4-01, 0.2 g Cunaphtenate (8%), 1 g N,N diethyl acetoacetamide and 0.03 g imidazole.After stirring the mixture for 5 minutes the reactivity of the mixturewas determined with the geltimer using 2% Butanox M50: Tgel=16,Tpeak=24.9 and peaktemperature of 122° C.

EXAMPLE 24

A formulation was prepared based on 100 g Synolite 8388, 0.2 g Cunaphtenate (8%), 1 g N,N diethyl acetoacetamide and 0.03g imidazole.After stirring the mixture for 5 minutes the reactivity of the mixturewas determined with the geltimer using 2% Butanox M50: Tgel=16,Tpeak=24.9 and peaktemperature of 122° C.

Example 23 and 24 demonstrate that the cure system according to theinvention can be used advantageously in combination with 1,3-dioxocompounds.

EXAMPLE 25

A formulation was prepared based on 90 g resin A, 10 g styrene, 0.22 gCu naphtenate in spirits (8%), 0.04 g imidazole and 0.98 g N,Ndiethylacetoacetamide. After stirring for 5 min the reactivity of themixture was determined with the geltimer using 3% Butanox M50: Tgel=7.4min, T peak=13.8 min and peak temperature of 167° C.

From comparing example 15 with example 25 it is evident that 1,3 dioxocompounds like N,N diethylacetoacetamide make the curing more effective.

1. A process for radically curing a resin composition, comprising thesteps of: (a) providing a two-component composition having a firstcomponent comprised of a resin composition comprising an unsaturatedpolyester resin and/or a vinyl ester resin, and containing less than0.001 mmol cobalt per kg primary resin system, and a second componentcomprising an organic peroxide; (b) subjecting the first component toperoxide curing by bringing the first and second components of thetwo-component composition into contact with one another, and (c)accelerating the peroxide curing of the resin composition of the firstcomponent by incorporating into the first component prior to step (b) anaccelerator combination comprised of a soluble copper compound and aheterocyclic aromatic amine in an amount sufficient to effectaccelerated peroxide curing of the first component according to step(b).
 2. The process according to claim 1, wherein step (b) is effectedat a temperature in the range of from −20 to +200° C.
 3. The processaccording to claim 1, wherein the heterocyclic aromatic amine is acompound according to formula 1:

in which each of A and B is N or CR, provided that at least one of A andB is N; and R, R₁, and R₂ are C₁-C₂₀ alkyl, C₆-C₂₀ aryl , C₇-C₂₀alkylaryl, or C₇-C₂₀ arylalkyl in which the aryl groups can be furthersubstituted, and in which a ring structure can be formed between R₁ andR₂, R₁ and R, R₂ and R and/or R₁, R₂ and R.
 4. The process according toclaim 1, wherein the heterocyclic aromatic amine is present in an amountbetween 0.001 and 1000 mmol/ kg primary resin system.
 5. The processaccording to claim 1, wherein the heterocyclic aromatic amine isimidazole or a derivative thereof.
 6. The process according to claim 1,wherein the soluble copper compound is an organic copper compound. 7.The process according to claim 6, wherein the organic copper compound isa copper carboxylate.
 8. The process according to claim 1, wherein thesoluble copper compound is present in an amount between 0.001 and 2000mmol/kg primary resin system.
 9. The process according to claim 1,wherein the copper and heterocyclic aromatic amine are present in amolar ratio of copper to heterocyclic aromatic amine of between 0.5 and50.
 10. The process according to claim 1, wherein the acceleratorcombination further comprises a 1,3-dioxo compound.
 11. The processaccording to claim 10, wherein the 1,3 dioxo compound is at least oneselected from the group consisting of 1,3-diketones,1,3-dialdehydes,1,3-ketoaldehydes, 1,3-ketoesters, and 1,3-ketoamides.
 12. The processaccording to claim 1, wherein the first component further comprises aninhibitor.
 13. The process according to claim 12, wherein the inhibitoris selected from the group of phenothiazines, phenols, hydroquinones,benzoquinones, catechols and N-oxyl compounds.
 14. A process forpre-accelerating a resin composition comprised of an unsaturatedpolyester resin and/or a vinyl ester resin and containing less than 0.01mmol cobalt per kg primary resin system, the process comprisingincorporating into the resin composition an amount of an acceleratorcombination comprised of a soluble copper compound and the heterocyclicaromatic amine in an amount sufficient to effect accelerated peroxidecuring of the resin composition.
 15. The process according to claim 14,wherein the heterocyclic aromatic amine is a compound according toformula 1:

in which each of A and B is N or CR, provided that at least one of A andB is N; and R, R₁, and R₂ are C₁-C₂₀ alkyl, C₆-C₂₀ aryl, C₇-C₂₀alkylaryl, or C₇-C₂₀ arylalkyl in which the aryl groups can be furthersubstituted, and in which a ring structure can be formed between R₁ andR₂, R₁ and R, R₂ and R and/or R₁, R₂ and R.
 16. The process according toclaim 14, wherein the heterocyclic aromatic amine is present in anamount between 0.001 and 1000 mmol/ kg primary resin system.
 17. Theprocess according to claim 14, wherein the heterocyclic aromatic amineis imidazole or a derivative thereof.
 18. The process according to claim14, wherein the soluble copper compound is an organic copper compound.19. The process according to claim 18, wherein the organic coppercompound is a copper carboxylate.
 20. The process according to claim 14,wherein the soluble copper compound is present in an amount between0.001 and 2000 mmol/kg primary resin system.
 21. The process accordingto claim 14, wherein the copper and heterocyclic aromatic amine arepresent in a molar ratio of copper to heterocyclic aromatic amine ofbetween 0.5 and
 50. 22. The process according to claim 14, wherein theaccelerator combination further comprises a 1,3-dioxo compound.
 23. Theprocess according to claim 22, wherein the 1,3 dioxo compound is atleast one selected from the group consisting of1,3-diketones,1,3-dialdehydes, 1,3-ketoaldehydes, 1,3-ketoesters, and1,3-ketoamides.
 24. The process according to claim 14, wherein the firstcomponent further comprises an inhibitor.
 25. The process according toclaim 24, wherein the inhibitor is selected from the group ofphenothiazines, phenols, hydroquinones, benzoquinones, catechols andN-oxyl compounds.